The present invention relates to the field of thermostats, and in particular to a method and apparatus providing automatic transmission of temperature information to a thermostat.
Typical thermostats for home or light commercial use generally are provided with a local temperature sensor within the thermostat housing to measure air temperature and adjust the climate control system attached thereto according to specified thermostat settings. These systems are limited in their application and oftentimes the thermostat is located such that temperature measurements are taken in less desirable areas of a building (e.g., in a hallway and not in the family room).
Systems were then developed that allowed for measuring temperature or other climate conditions in multiple rooms or on multiple floors of a building. For example, some homes are provided with a separate thermostat on each floor of the house, each of which individually controls the climate settings for the respective floors of the house. In other applications, multiple external sensors hardwired to a thermostat may be provided to transmit temperature or climate information from different rooms or floors of a building for use by the thermostat in controlling climate conditions. However, as the number of sensors required for a particular application grows and/or the retrofitting required becomes more complex (e.g., multiple sensors on multiple floors controlled by a single thermostat), the cost for hardwiring the sensors is increasingly expensive and installation increasingly complex.
Sensors were then designed for transmitting temperature information from a remote location separate from the digital thermostat, without the need for any wires, for example by using radio frequency or infrared signals. Although this reduces the cost of installing the sensors, problems arose with accommodating transmissions and avoiding transmission interference and collisions from multiple sensor in the same house or building, each having its own transmitter. The use of sensors transmitting on multiple frequencies or at different time periods reduces transmission collisions. However, if an apartment complex has a wireless thermostat system encompassing four sensors for each apartment, with 50 apartments in the transmitting radius, then at a minimum, 200 unique frequencies must be selected to prevent one from interfering with the other. Although this reduces the problem of transmission collisions, the cost for providing these unique frequencies is high, as the sensors would have to provide for selecting the unique frequencies (e.g., a dip switch, keypad or display for selecting the frequencies). Further, transmitters capable of supplying these different frequencies would also have to be provided.
The known systems fail to provide efficient and adequate variable time sensing of temperature and random remote transmission of temperature information, while also providing user control of the sensor settings. Therefore, what is needed is a method and device for providing automatic remote temperature sensor transmission of temperature information, with transmission on variable frequencies only on a change in temperature. The method and device needs to provide efficient transmissions, while minimizing interference and allowing control of the remote temperature sensors.
The present invention provides for the use of multiple remote temperature sensors that minimize transmission interference, while improving individual control of the sensors by allowing programming of each sensor by a user according to the user""s specific temperature requirements (e.g., a user desiring to cool a room in which there is a remote sensor simply adjusts the temperature at the remote sensor to transmit adjusted temperature information). The present invention provides a remote temperature sensor preferably having a liquid crystal display for indicating temperature and other control information. The sensor preferably uses a transmitter (e.g., radio frequency transmitter) to transmit temperature and associated information to a host-controlling thermostat only on a sensed change of temperature. The temperature is also sensed at variable time periods which may vary only minimally.
The sensor may be provided such that an offset can be made to the temperature at a remote sensor to raise or lower a sensed temperature transmitted, thereby effectively adjusting the temperature information transmitted in a particular room as desired or needed. Further, the invention may provide for weighting each temperature sensor, such that the temperature information transmitted from one sensor is given more weight in adjusting the climate control system than another sensor.
Succinctly, the invention provides both a method and device for use in connection with a thermostat for controlling a climate control system, which includes remote temperature sensors that may be programmable, and that transmit temperature information with minimized interference. Specifically, the invention is preferably provided such that a unique serial number and/or channel number information is transmitted along with the temperature information on a variably selected frequency (e.g., random frequency) within a fixed range. Further, sensing of air temperature may be provided at variable time intervals (e.g., a time offset provided based on a previous sensed temperature) and transmission of the sensed temperature transmitted only on a predetermined temperature change (i.e., comparing the current sensed temperature with a previously transmitted temperature and transmitting only upon a predetermined change). Thus, the possibility of transmission collisions is reduced or eliminated.
Additionally, the present invention may be provided with a learn mode such that the host-controlling thermostat may initially identify each sensor for later recognition of transmitted temperature information from each of the sensors. Each sensor may also be provided with a plurality of power transmission levels, giving the invention further adaptability and increased utility in retrofit applications.
While the principal advantages and features of the present invention have been explained above, a more complete understanding of the invention may be obtained by referring to the description of the preferred embodiments which follow.